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Jan. 31, 1956 A. e. BILLIN RECIPROCATING BUCKY ACTUATOR Filed Feb. 20,1952 (5 Sheets-Sheet 1 ,-& /2

{1 12 4 s4 25 12 1 70 105 12. A 11 so 6 w-nfii wi uua INVENTOR.

ATTOQNEYS.

Jan. 31, 1956 A. G. BILLIN RECIPROCATING BUCKY ACTUATOR 3 Sheets-Sheet 2Filed Feb. 20. 1952 A m p m m 3 l 8 m u l um Qm do (am; up 2 2 8INVENTOR. M 9. Whi

ATTORNEYS- Jan. 31, 1956 A. s. BILLIN 2,733,352

RECIPROCATING BUCKY ACTUATOR Filed Feb. 20, 1952 5 Sheets-Sheet 3 WWZOTPUwZZOU wad m.

United States Patent This invention relates to photograph-stItis-directe 1 mechanismfor phragms is helpful:

A conventional diaphragm, termed 7 in respect to the name ofits-inventonconsists: of-a p1urays generated at the tube. a subject,some by producingso-calledsecondary radiations whichwould strips of aBucky diaphragm would cast eopaque' their shadows upon the film iftionary during ment of the-film, the- However,.in passing through'X-rays are scattered or deflected, there 2583,352- Patente'd Jan; 31,1956 However, such inconvenient and'uncertain.

A-diflicultproblem is encountere'd'in-all X-ray pho'tdgraphyutilizing-aBucky diaphragm because of 1 the puls'af- Sincesuchtubes ternatingvcurrent; usually 60 cycl if an X-ray pulsationhappens to does,- just when the Jay'opaqueare operated upon' al c; it isapparentthat posures; e.- g. nature;

lngtnatureof the X-ray: emanations' generatedlay the tube medium. Aphotocell, focused upon this screen, generates a current in proportionto the light emitted from the screen, and such current is employed inthe charging of a condenser in a control circuit. When the charge uponthe condenser reaches a critical value, which is adjusted in respect tothe known sensitivity of the photographic medium, the control circuit isenergized to terminate the exposure. The arrangement, therefore,constitutes an automatic exposure meter which eliminates the need forthe operator to exercise his independent skill or judgment.

It will be apparent that a conventional single-pass Bucky diaphragm isvery difiicult, if not impossible, to use successfully in photographinga variety of subjects with phototirned X-ray equipment, since theoperator has no means of determining the rate or duration of movement ofthe diaphragm necessary to accommodate an unknown, but automaticallyterminated, exposure governed by the phototimer.

To accommodate the longer exposure periods, several mechanisms have beenproposed for reciprocating the diaphragm back and forth over the filmwhile the X-ray tube is energized. However, the results obtained withsuch apparatus have generally been quite unsatisfactory because of theincidence of synchronism and because of the inherent tendency forimperfect pictures to be produced when exposure happens to be started ata moment of reversal of the direction of movement of the diaphragm. Adiaphragm is quite heavy, embodying as it does a substantial number oflead strips plus a frame in which the diaphragm is supported. By virtueof such weight, momentum and inertial forces are involved which must beovercome in first bringing the diaphragm to rest at the end of a strokein one direction and in then causing the diaphragm to reach intendedspeed in the opposite direction. The rates of deceleration andacceleration of the devices proposed in the past have been so slow thatundesirable conditions of synchronism occur during the reversal periodswhen the diaphragm is moving at less than intended speed, or so fastthat undesirable vibration is established.

The present invention embodies a Bucky actuating mechanism which is ofutmost simplicity and which is relatively inexpensive to construct, yetwhich provides singularly desirable results in the elimination ofsynchronous conditions. The apparatus of the present invention isactuable either for short or long exposure periods and operates theBucky diaphragm reciprocably during an exposure period at substantiallyuniform rates of speed in opposite directions, but provides rates ofdeceleration and acceleration of the diaphragm, such that undesirableshadow efiects are substantially prevented from occurring duringreversal periods.

Reduced to its simplest terms, the diaphragm actuator of the presentinvention consists of a reversible drive motor, control devices whichgovern the direction of power movement of the drive motor, and which, inturn, are governed by the diaphragm when it reaches the respective endsof its strokes in opposite directions, and a simple string connectionthrough which the power of the drive motor is imparted to the diaphragmfor reciprocating it. The power motor drives the diaphragm through thestring connection at a rate which may be the same, or substantially thesame, in one direction as in the other, but the limited resiliency ofthe string, plus prompt reversibility of the motor, enables sufficientlyhigh acceleration and deceleration to be obtained in the reversalperiods to eliminate undesirable mechanical and photographic resultswhich would otherwise be obtained by an inelastic or positive connectiontype of drive.

The actual rate of movement imparted to the diaphragm is non-synchronouswith respect to the X-ray frequency; that is, the rate of movement ofthe Bucky does not hear an integer or simple sub-multiple relation tothe frequency of pulsations of the X-ray tube, or otherwise coincidencein the positions of the grid strips might lead to incidence of shadowsduring passage of the diaphragm in either direction. Also, it isdesirable that the rate at which the diaphragm is movable be greatenough to cause a sufficient number of opaque strips of the diaphragm topass a given point on the subject or film and thereby provide properscreening of secondary radiations from the film.

A further feature of the present invention resides in apparatus capableof returning the diaphragm to a predetermined starting position at theend of an exposure period, no matter where the diaphragm happens to beat the moment exposure is terminated. By means of this feature of theinvention, the position from which the diaphragm will start to move inthe next successive utilization of the apparatus is established andvariations or undesirable results which might otherwise occur throughvariations in the starting position are eliminated. This feature isparticularly important when a short exposure is to be made.

The invention also contemplates a mechanism in which the Bucky willassume movement at a desired speed before X-ray exposure can commence,thereby eliminating the incidence of shadows on the film throughinadequate Bucky movement at the very start of an exposure.

From the foregoing principles upon which the present invention ispredicated, and the following detailed description of the drawings inwhich a preferred embodiment of the invention is disclosed, thoseskilled in the art will readily understand the modifications to whichthe invention is susceptible.

In the drawings:

Figure 1 is a plan view of a diaphragm actuating mech anism of thepresent invention.

Figure 2 is a sectional elevation taken on the line 22 of Figure 1.

Figure 3 is a sectional elevation taken on the line 3--3 of Figure l. a

Figure 4 is a sectional elevation taken on the line 4-4 of Figure 1.

Figure 5 is a sectional elevation taken on the line 5-5 of Figure 1.

Figures 6 and 7 are simplified, somewhat diagrammatic views, showingactuation of reversal switches by the diaphragm in respective phases ofits movement, and

Figure 8 is a circuit diagram illustrating a control circuit throughwhich reversal of movement is accomplished in conjunction with return ofthe diaphragm to starting position at the end of an exposure.

The diaphragm with which the actuator mechanism of the present inventionis attached to be used may be of any suitable type, and is indicatedgenerally in the drawings at 1. The diaphragm is equipped with aperipheral frame 2, and a longitudinal edge 4 of the frame is providedwith spaced guide blocks 6 and '7 through which the diaphragm movablyis-mounted. The diaphragm 1 is contained within an overall frame orhousing 8, which is made up, for example, of plates or channel irons ofsuitable configuration, all joined together by bolts or welding.

The overall frame 8, as will be noted from Figure l, is both longer andwider than the screen diaphragm l, the additional length providing a thediaphragm, and the additional width providing space, indicated generallyat 9, within which components of the actuating and control mechanism arehoused. The area 9 is delineated from the remainder of the overall frame8 by a dividing wall It the top of which is spaced from the bottom ofthe diaphragm 1.

Guide blocks 6 and 7 are bored longitudinally to receive guide rods 11which are supported rigidly upon pairs of brackets 12, 12 extendingupwardly from the face of the dividing wall 10. The rods 11, therefore,'slidably support the diaphragm along one longitudinal edge thereof,Similar guide rods may be provided to sustain the field of movement ofc'arry plate members 161 to y means of screws 18. In the trated; each ofplates 16 and 17 has an attachment post 19,-;l9--extending from it, and'a string 'drivemember 20 or otherwise suit- 21 or anchoredhto it, drivesheave is'actuated by meanso'f 1n nuts,,-a s at 24 (Figure 3).

The string of drive member 20 is p'referably in-the form of -a fibrouscord having sutficient-pliability to pass around the drivesheave 21, andsuiiicient strength to withstand the forces to whichit is subjected incausing the diaphragm to reciprocate. Braided cord fabricatedof postsand 31 extending speed -'reduction; geartrain e i gear' train,

to note-th'at the reversible electric motor drives the gear trai'n andthe gear train, in turn, drives the sheave "21 around-which the string20 is wound for frictional engagementtherewith.

Thespeed reduction provided by the gearing 2': is jap in drivingconnection with the sheave 21 propriate, in relation to the'diameter ofthe drive sheave 21' to cause linear movement of the string, andattendant linear movement of the diaphragm 1, at a rate which isnon-synchronous with respect to the pulsations of the timing of theactuation of these moved to the right. eration of switches 36 and 37which are obtained in this I larly on a post (not shown) at the oppositeend of switch 44 and at the opposite side thereof from post 58. Lever 57extends along the switch and terminates in an offset portion 68 which isactuated when the diaphragm reaches the right hand end of its stroke.

The levers 56 and 57 are served by an actuator assembly 62 which issupported on plate 17, the latter being fastened to the face of guideblock 7 as previously described. Actuator 64 extending over and aboveswitch 44, and finger members 66 and 67 are mounted on the shelf, thefinger members respectively providing fingers 63 and 69 which arepositioned for engagement with the ofiset portions 59 and 6% of therespective levers 56 and 57. The finger members 66 and 67 are fastenedto the shelf 64 by means ofscrews 7t) which pass through appropriateslots 71, thereby permitting the relative positions of thc fingermembers to be adjusted for timing purposes. When diaphragm 1, in movingto the right, reaches the end of its intended stroke, the dependingfinger 69 engages the offset portion 60 of actuating lever 57, theswitch 44 is thrown, and this promptiy causes reversal of motor 27, asdescribed at a subsequent point in the specification. Similarly, whenthe diaphragm, after moving to the left, reaches the end of its strokein that direction, the finger 63 engages the offset portion 59 of lever56, throwing the switch 44, and thereby again reversing the direction ofmotor rotation. Since the switch 44 is of the snap action type, itremains in any position in which it may be set until it is next actuatedto the opposite position.

A relay 72, which is employed in the preferred electrical circuit of theapparatus, may be positioned in the housing area 9 and, to facilitatepower connections to the entire apparatus, a plug receptacle 73 may alsobe mounted in the front wall of the overall frame 3. To avoid confusionin the illustration of the mechanical parts, the wiring connections arenot illustrated in Figures 1-7, though it will be noted that the housingarea 9 provides ample space for wiring without interference thereof withthe movable parts of the apparatus.

Electric circuit An X-ray machine is provided with a primary controlswitch which, for present purposes, is indicated generally at 75. Thiscontrol switch may be operated either manually or by a mechanical timeror by photoelectric timing means. In addition, an X-ray tube is usuallypowered through a magnetic switch or other suitable contactor, which isindicated generally at 76. For the purpose of illustrating the operationof the present apparatus, these elements are shown in the circuitdiagram of Figure 8. Operating voltage is supplied through leads 77 and72*, while the leads from the control switch 75 are designated 79 and86. All of these connections may be made through a plug (indicateddiagrammatically), which is engageable with the plug receptacle '75 ofthe apparatus.

Input voltage leads 77 and 78 are connected directly to the fieldwinding 81 of the motor 27, while lead 79 from the control switch 75 istaken to one terminal of relay 72, which is a single pole, double throwrelay. The opposite terminal of the relay 72 is in connection with inputlead 73, as at 33, arid is also in connection, through lead 84, with oneof the contacts 35 of the exposure switch 37. One terminal of themagnetic switch 76 of the X-ray apparatus is in connection through lead86 with the other of the contacts of the exposure switch 37,

and the opposite terminal of the magnetic switch is in connection withinput lead 79 of the control switch 75 through lead 87.

Thus, the field winding 81 of motor 27 is connected directly acrossinput terminals 77 and 78, while switches 75 and 37 are in a seriescircuit extending from input terminal 78 through junction 83 to switch37 through lead 84, and from lead 86 of switch 37 through magneticassembly 62 includes a shelf portion switch 76 to lead 87 which passesto lead 79 for control switch 75, the latter being connected to inputterminal 77 through lead 80. Relay 72 is connected across junction 33and lead 79, and therefore, is in parallel with switch 37 and coil 76 inseries.

As previously noted, the motor 27 of the power .unit 22 embodies shadingcoils which are magnetically coupled with the field winding 81 and whichgovern the direction ofmotor rotation. These shading coils aredesignated 89 and 90,- the common connection between them beingdesignated 91. When the circuits to both coils are open, the motor 27 isidle, but when either coil is short circuited, the motor will run. Thecoils are so wound or arranged that short circuiting of one will causethe motor to run in a direction of rotation WhlCh is opposite thedirection of rotation prevailing when the other coil is short circuited.The electric circuit is arranged to cause short circuiting of thesecoils through actuation of cycling switch 44. For this purpose, thecommon terminal 91 of the shading coils 89 and is in connection througha lead 92 to the movable armature 93 of relay 72. The movable armatureis biased in one direction, for instance by means of spring 94, but whenthe relay winding 95 is energized, the armature 93 of the relay isattracted sufiiciently to overcome the bias of the spring 94. Thereby,the armature 93 alternately serves the two contacts 96 and 97 of therelay.

Contact 96 of the relay is in connection with the movable contact ofhoming switch 36 through a lead 99. The other contact of the homingswitch is connected as at 1613 to the end of the shading coil 89opposite the common connection 91 thereof. The other contact 97 of therelay 72 is in connection through lead 101 to movable contact arm 102 ofcycling switch 44. This cycling switch, as previously noted, is of thedouble throw type, having two stationary contacts 103 and 104,with'which the contactor arm 102 alternately makes engagement; Contact103 is connected through lead 105 to the end of shading coil 99 which isopposite the common terminal 91, while contact 104 of the cycling switchis connected through lead 106 to the junction at which lead from thehoming switch 36 joins the shading coil 89.

Description of operation When the diaphragm is at rest, preceding usageof the apparatus, exposure switch 37, and homing switch 36 are open, andthe contact 93 of the relay 72 is in engagement with contact 96 thereofunder the influence of spring 94. For purposes of the description, it isassumed that the contactor arm 192 of cycling switch 44 is in down"position, in engagement with contact 103 thereof. The circuit of shadingcoil 89 is open at the cycling switch 44, and the circuit of shadingcoil 90 is open at relay 72. The field of motor 27 is energized throughthe leads 77 and 78, and the apparatus is ready for operation.

As soon as control switch 75 is closed, either manually, mechanically,or electrically, relay 72 is energized caus-' ing contactor 93 thereofto make engagement with contact 97 against the bias of spring 94. Thisoperation causes shading coil 90 to be short circuited, the circuitextending from the mid connection 91 through lead 92 to armature 93 ofrelay 72, and through lead 101 and contacts 192 and 103 of the cyclingswitch 44, thence back to the shading coil 90 through lead 105. Shortcircuiting of the shading coil 90 causes the motor to operate thediaphragm to the right, for example as shown by the arrow adjacentshading coil 99 in the drawing.

Shortly after the diaphragm starts to move, the arms 43, 48,respectively controlling homing switch 36 and exposure switch 37, arereleased, and these switches close. Closure of the exposure switchcompletes a circuit to the magnetic switch 76 of the i 84, and 87, ar1dcontrol switch 75, thereby energizing the X-ray tube, only after thediaphragm is in motion.

Closure of homing switch 36 conditions the circuit so X-ray tube throughleads 86,-

9 that it subsequently may be governed, by, the, homing switch.

Placed in motion,

Atthis time, finger, the lever 57,

otherpositiont, This; ineflect, causescontact arm102 otlcyclingswitch-M,as shown. in Figure 8,;to break enga ment, withcontact 103.,andamake engagement with contact 104. Since, the relay,72.,is energized,contact 93 75.,is, closed; hence-there is no limit on the timeduzingwh-ichithe.diaphragm, maybe oscillated back and fOl'tha,

right or left as; the case'may be; arrangedthatthe diaphragm, Whateverits position,

of; the, apparatus in the. next usage.

To illustrate. theoperation of-the homing featureof the circumstance,cycling switch44 Will he down?; position, 115e,, contact 102'thereofiwill be allowing the diaphragm to come to rest.

When the diaphragm is moving to the left, the cycling now opened, relay72 is de-energized and contactor 93 moves into engagement with contact96, which re-estabtheright untilj'ittreaches the right hand .endof itsHowever, the diaph tuates it so that it when the apparatus is nextused.v

From this description,

move the Bucky from.

fr me,

tric motor and a diaphragm driven thereby in opposite directions, areciprocation control circuit including switch means for energizing themotor to cause it alternately to operate in opposite directions, and ahoming circuit including said electric motor and a homing switch whichis responsive to movement of said diaphragm for completing a circuit tosaid motor following reciprocating operations thereof and efiectivethereafter to cause continued motor operation suflicient to drive thesaid diaphragm to a predetermined position.

4. Mechanism for reciprocating a Bucky grid continu ously during anX-ray exposure, comprising a base having means for slidably mounting aBucky grid therein, a reversible electric power unit mounted in saidbase, a string drive member connecting the said power unit to said Buckygrid for imparting movements in opposite directions to said grid fromsaid power unit, reversing switch means in electrical connection withsaid power unit, an actuator for said switch means secured to said grid,whereby reversal in the direction of movement of said electrical powermeans is effected at predetermined points in the movement of said grid,the said string being of limited elasticity for absorbing the momentumof the moving Bucky grid, means for initiating and terminatingreciprocating movement of said power unit, and homing switch means forcontrolling movement of the said grid to a predetermined position afterits reciprocating movements are terminated, whereby movement of the gridin a next successive usage of the mechanism commences from apredetermined point.

5. Mechanism for reciprocating a Bucky grid continuously during an X-rayexposure, comprising a base having means for slidably mounting a Buckygrid therein, a reversible electric power unit mounted in said base, astring drive member connecting the said power unit to said Bucky gridfor imparting motor movements in opposite directions to said grid fromsaid power unit, reversing switch means in electrical connection withsaid power unit, an actuator for said switch means secured to said grid,whereby reversal in the direction of movement of said electrical powermeans is efiected at predetermined points in the movement of said grid,the said string being of limited elasticity for absorbing the momentumof the moving Bucky grid, means for initiating and terminatingreciprocating movement of said power unit, an homing switch meansindependent of said reversing switch means.

6. Mechanism for reciprocating a Bucky grid continuously during an X-rayexposure, comprising a base having means for slidably mounting a Buckygrid therein, a reversible electric power unit mounted in said base, ataut, slightly stretchable string connecting the said power unit to saidBucky grid for imparting movement to said grid in opposite directionsfrom said power unit, re versing switch means in electrical connectionwith said power unit, an actuator for said switch means secured to saidgrid whereby reversal in the direction of movement of said electricalpower means is effected at predetermined points in the movement of saidgrid, means for initiating and terminating reciprocating movements ofsaid grid from. said power unit through said string, and a homingcircuit including said motor and a homing switch which is independent ofsaid reversing switch means for maintaining motor operation aftertermination of reciprocating movements of said grid until the said gridreaches a predetermined home position.

7. In an X-ray machine, the combination of a Bucky grid, means forreciprocating said grid including a reversible electric motor, areciprocation control circuit including switch means for energizing themotor to cause it alternately to operate in opposite directions, ahoming swith in parallel control connection with said reciprocationcontrol circuit, a control switch for initiating and terminating motoroperation, means actuable in response to the condition of said controlswitch for alternately placing said homing switch and said controlcircuit in operative control relationship with said reversible motor.

8. In an X-ray machine, the combination of a Bucky grid, means forreciprocating said grid including a reversible electric motor, saidelectric motor having two shading coils, a reciprocation control circuitincluding switch means for alternately short circuiting one or the otherof said shading coils to cause the motor alternately to operate inopposite directions, a homing circuit for short circuiting one of saidshading coils to cause said motor to drive said Bucky to a predeterminedposition after its reciprocating movements are terminated, said homingcircuit including a homing switch operable upon Bucky movement tocondition the homing circuit for control of the motor, a control switchfor initiating and terminating motor operation, relay means actuable inresponse to the condition of said control switch for rendering saidreciprocation control circuit ineffective for control of said mtor andplacing said homing circuit in efiective circuit relationship with saidshading coil upon opening of said control switch.

9. Mechanism for reciprocating a Bucky grid continuously during an X-rayexposure, comprising a base having means for slidably mounting a Buckygrid therein, a reversible electric power unit mounted in said base,means including a string drive connecting the said power unit to saidBucky grid for imparting movements in opposite directions to said gridfrom said power unit, reversing switch means in electrical connectionwith said power unit, an actuator for said switch means secured to saidgrid, whereby reversal in the direction of movement of said electricalpower means is effected at predetermined points in the movement of saidgrid, said string drive means being of limited elasticity for absorbingthe momentum of the moving Bucky grid, means for initiating andterminating reciprocating movement of said power unit, and means foreffecting movement of the said grid to a predetermined position afterits reciprocating movements are terminated, whereby movement of the gridin a next successive usage of the mechanism commences from apredetermined point.

References Cited in the file of this patent UNITED STATES PATENTS2,123,182 Drake July 12, 1938 2,203,689 MacDonald June 11, 19402,205,209 Kunz et al June 18, 1940 2,334,447 Shaw Nov. 16, 19432,504,864 Morgan et al Apr. 18, 1950 2,583,213 Graves Jan. 22, 1952FOREIGN PATENTS 305,322 Great Britain Feb. 7, 1929 495,215 Great BritainNov. 19, 1938

